Headlight



H. L. COOKE Nov. 5, 1940.

HEADLIGHT Filed July 26, 1938 INVENTOR Coo/f5 BY l www ATTORNEYSPatented Nov. 5, 1940 UNITED STATES HEADLIGHT Hereward Lester Cooke,Princeton, N. J.

Application July26, 1938, Serial No. 221,283

Claims.

This invention relates to light projecting devices and has specialreference to headlights for use on automobiles wherein provision is madefor a single beam of light of predetermined bril- 5 liance and directionand a non-glare annular band of diffused light surrounding said beam. Itrelates more particularly to the type of lamp wherein the source oflight and the reflector are combined in a single unit so that theconventional reector combined with a separate bulb may be dispensedwith.

In my prior Patent No. 1,712,027 of May '7, 1929, I have disclosedheadlights having paraboloid reecting surfaces with concentratedfilaments or other convenient sources oi light at the foci of saidparaboloids and front surfaces of ordinary form. I also disclosed insaid patent the incorporation in such a lamp of an internal shield infront of the filament whereby only those rays reected by the paraboloidcan emerge from the lamp, direct rays from the iliament beingintercepted by said internal shield. While this arrangement, by cuttingout the direct illumination, shields the eyes of oncoming drivers fromglare, it has the disadvantage that,

particularly with good designing, the -wide angle of illumination asopposed to the beam or columnar illumination is apt to be so faint as toendanger the car from obstructions close to 3o the car but out of thedirect beam of the reflected light, such as overhanging branches and thelike, and thus perception of objects outsidethe region of calculatedintense illumination is rendered dimcult.

My invention is not necessarily to be limited -to the use of a lightcomprising an integral light source and reector. It is also applicableto the customary automobile headlight or other lights comprising aconventional electricI bulb 40 and a reflecting surface. However,certain distinct advantages result from applying my inventionto integrallight source and reflector systems in that the absence of surfaces ofglass between the light source andthe reflector, such as the outer andinner surfaces of a bulb, avoids diiraction and multiple reflection andincreases Y the sharpness of the collimation. In lights employing bulbs,wide angle illumination depends on stray rays resulting fromdiffractions and multiple reflections and from direct rays from theunshielded filament, but since no control over the amount or directionof light so diffracted or directly emitted is obtained, glare is verylikely to result. According to my inven.

tion in integral light source and reector systems, especially wheredirect rays are intercepted by a shield, all rays are iirst broughtunder control and collimated by the reflector. A specified portion ofthese controlled rays is then diffused or spread. Thus the rays directediat- 5 erally for wide angle illumination may be controlled exactly bothin intensity and direction. Owing to this denite control and to the factthat the main beam itself is sharply defined and composed of completelycollimated rays, it 10 is possible to greatly increaselthe candle powerof headlights which may be used with safety on the highways. Thispermits faster and safer night driving. l

It is an object of this invention to provide a l5 light projectiondevice or headlight which shall have combined with a collimated beam ofpredetermined direction and intensity an additional zone of diffused orspread rays which alsomay be of predetermined intensity whereby lightmay 20 be directed over any required solid angle ahead of an automobile.It is a further object of this invention to provide an integral bulb,reflector and lens capable of producing a collimated beam of desiredintensity and direction, in which the z5 direct rays of the light sourceare shielded to prevent glare, having a pebbled or otherwise striatedzone upon the lens portion of the bulb adapted to change the directionof the rays passing through that portion in a random or calcua0 latedmanner, thereby producing in that portion of the lens a zone ofsubstantially glareless diffused illumination. Further objects andadvantages will appear from the description and drawing in which- 35Fig. 1 is a horizontal section of an embodiment of a lamp having myimprovement applied thereto;

Fig. 2 is a vertical section of the same embodiment; o

Fig. 3 is a front view of the lens shown in Figs. l and 2:

Fig. 4 is a front view of a part of an optional form of lens;

Fig. 5 is a. side view of the front part of an 45 automobileillustrating diagrammatically an example of light distributionobtainable by use of the lamps of this invention.

Fig. 6 is a front view showing how the lamp will appear to the occupantof an oncoming car 50 when illuminated at night, the lens of the lamphaving a conventional design applied thereto; and

Figs. 'I and 8 are fragmentary front Views ilin the art, or to bemountedin a proper socket in any convenient manner. The rear wall Il ofthe lamp is preferably. in the shape of a paraboloid or parabola ofrevolution, and the light source il, which may be in any convenientform, here shown as a filament, is mounted upon the support l5 which hassuch length and position that the center ofthe filament is as nearly aspossible at the focal point of the paraboloid. Where a filament is used,it is preferably as compact as possible and may be of any known kindwhich approaches the ideal condition of a point source of light. Asshown in Figs. 1 and 2. the filament i4 may preferably have its longeraxis horizontal, but any suitable approximate point source of light maybe used.

The exterior or preferably the interior surface of the rear wall I 3 issilvered or otherwise made a reflecting surface and serves thereby toreflectV the rays of light from the source i4 and to form them intoasubstantiallyparallel vor collimated beam of light which passes throughthe nonsllvered frcnt portion i6 of the bulb. In order to cut off thedirect rays emanating forwardly from the source of light, which wouldnot be collimated, I preferably provide a shield IT of opaque ordarkened transparent material which' maybe located as shown in Fig. 1between the source of light I4 f and the non-silvered part of the bulbI6 through which the reflected rays are directed. This shield may be ofany suitable form, such as the spherical form shown, and may be mountedin any convenient fashion, it being the purpose of the shield to cut offall rays from the source of light which would otherwise pass directlyout of the bulb without striking the reflector. l

The front of the bulb may suitably be formed into a lens by striationsor prisms or in any other convenient manner. By modifying the form ofthe lens the colllmated rays may be directed in a variety ofconfigurations and directions accordlng to the use to which the bulb isto be put. When used in automobile headlights I have found it preferableto design the lens portion of the bulb so that the collimated rays maybe yslightly depressed in order to avoid glare in the eyes of theoncoming driver and laterally spread to a small extent in order to lightthe desired width of the road.

With the described arrangement of shield and reflector the directillumination from the source tion dilcult.

of light is eliminated and a light is, achieved having a true collimatedbeam and lacking entirely the stray rays which cause the objectionableglare which in automobile lights tends to blind the oncoming driver.However, under these described, I propose to add to the lens I6 aportion I8 of pebbled or striated irregularities or definitely formedprismatic characteristics designed to diffuse the light passing throughit from the reflector in such amanner that this light leaves thecollimated beam and is spread laterally from said beam in random orpredetermined directions. The pebbles or striations of the lens portionIl may be so formed as to connne the laterally spread light withinsuitable angular limits such as the angle Il shown in Fig. l. I havefound it preferable to locate this striated or pebbled connguration ofthe lens Il partly or wholly about the circumference thereof either inthe form of an annulus, Fig. 3, or in various suitable designs, such asshown in Fig. 4, according to the requirements of the designer. Ifdesired, the lens may also be provided with a pebbled or vstriated areain the form of a design, a tradethrough the diffusion zone of the lensbut is so N effectively diffused that glare is prevented.

Figs. 7 and 8 illustrate possible arrangements of striations which maybe substituted for the pebbling in the area I8 and adapted to diffuse orspread the light at the margin of the lens. Fig. 'l shows suchstriations arranged radially and Fig. 8 shows them arrangedcircumferentially. Lay other suitable arrangement may also be used. Fromthe foregoing description it will be apparent that numerous advantagesarise from this type of light. The combination of reflector and lightsource in one integral system insures that there will be a fixedrelation between the light source and the reflecting surface so that therei'lected beam of light will not be subject to variations whichordinarily are caused by slight movements of a light source such as abulb in relation to the reflecting surface. This is a particularlysalient advantage when these lights are applied to automobiles as theJolting of the car during travel will not disturb the accurateadjustment between the light source and the reflecting surface. The useof an annulus of pebbling or striations which changes the direction ofthe outside portion of the collimated beam does not detract suiiicientlyfrom the strength of the beam to seriously ailect its lighting qualitiesas, in fact, the rays which are diffused in this manner are the weakestreflected rays from the reflecting surface i3. This Iarises from thefact that where a given quantity of light is to be diffused through anannular area such as I8, the apparent intrinsic brilliance of thisannulus will vary inversely as the square of the radius vector 22 fromthe light source Il to the center 23 of the annulus and the area i8 isthat part of the lens furthest from the light source. In addition to thecontrol of the portion of light used in the beam, absolute control ofthe portion of light used for. diffused illumination may also beobtained as the area of the' annulus and the configuration of thepebbling or striations may be conveniently adjusted to suit the needs ofthe individual light.` Furthermore, the angle of diuse illumination mayalso be very closely and carefully controlled by adjustment4 of thestriations or pebbling.

' As viewed from ahead, the light, when illuminated and in thesurrounding darkness, will have a distinctive and noticeable appearanceas illustrated in Fig. 6, the annular region I8 being bright but notdazzling, the intermediate region being faintly illuminated when viewedfrom a position above or at one side of the direct collimated beam,

and the central portion 2l which is over the shield I'I being black, thepattern of the intering an integral lens portion comprising a zone formodifying the ldistribution of the beam and mediate and central portionsbeing, of course, modied more or less by the prisms or striations 2| ofthe lens. The annular region I8, however, will be sharply dened.v andvery striking in' appearance. If the lens is provided with a pebbled orstriated design such as 30 or 3|, this design will appear bright likethe annulus i 8,

The resulting light distribution obtained from my new light isillustrated diagrammatically in Fig. 5 wherein is shown the beam 24which comprises the collimated rays which are reflected through the mainpart of the lens I6 and the cone or fringe of diffused rays 25 which arethose rays broken up and spread by the striations or pebbling I8 at themargin of the lens.

Where my invention is applied to an integral bulb and reflector, thelamp may be manufactured by blowing in a mould or by constructing thereflector I3 andlens i6 as two separate portions and fusing themtogether at their outer peripheries. or by any other suitable means.Parts I4 and l1 may suitably be placed in the reilector part of the bulbprior to the fusing process.

t While the invention is directed mainly to use in automobile headlightsit is,-of course. to be understood that it covers all lamp systems ofthis type, whether intended for automobile or other use. It is furthercontemplated by the invention that the reflecting surface need notnecessarily be paraboloid but may be of other shapes according to theneeds to which the lamp is applied and the position of the iilament orother source of light need not necessarily be concentrated in the focusof the paraboloid'although this arrangement is preferable. As beforestated, other sources of light than iilaments may be used such as theball of incandescent tungsten of the type used in certain lamps known inthe art.

I claim:

l. In a headlight. a glass bulb having an integral portion forreilecting rays in a substantially non-diverging beam, a concentratedsource of light therein at the focus of said reiiector, a

'shield interior of the bulb disposed in the path a diifusing zone.

2. An electric light comprising an integral bulb and reflector, a sourceof light located at the focus of said reilector, a shield to interceptunretlected rays, and a front lens portion, said lens portion comprisinga circumferential annular zone for difiusing light within predeterminedlimits and a central portion for passage of refiected light in acollimated beam.

3. An integral electric light comprising a paraboloid reflector, a lightsource at the focus of said reflector. a shield preventing the emergenceof direct rays from the light sourceand a lens through which thereflected rays pass, said lens comprising an annular zone for diiusingreflected rays in a random manner, and a zone for direct-f ing reilectedrays in a collimated beam of high brilliance.

4. An electric headlight unit comprising a paraboloidal reflector and afront lens united to form a sealed bulb, a filament located at the focusof said reflector, said lens having a central portion formed to emit acollimated beam of high intrinsic brilliance and a surrounding portionformed of a large number of irregular, smooth, transparent, refractingsurfaces acting to diffuse a part of the light coming from said unit ina random manner.

5. An electric headlight unit comprising a reilector for reflecting raysin a collimated beam,

and a lament therein at the focus of said reflector, said unit having alens united to the reflector to form a sealed bulb, said lens comprisinga prismed zone for modifying the distribution of the collimated beam soas to limit the upper boundary of the beam to a given level, said lensalso having a zone in the form of a definite pattern, said zon beingformed of irregular. smooth, transparent, refracting surfaces tothoroughly diuserays of light passing through the same,

whereby when the said headlight is viewed from a point in front of thesame, and above the upper boundary of said collimated beam, the patternof said diffusing zone will be clearly defined and plainly visible.

HEREWARD LESTER COOKE.

- A K y CERTIFICATE CE CORRECTION. Patent No. 2,220511'15. November 5,19u HEREwARp LESTER COOKE.

Itis hereby certified that error appears in the printed specification ofthe above numbered patent requiring correction as follows: Page 5,-first column, line )48,.c1ai 1., for the word "interior'I read exterior;and that' the said Letters' patent shouid be 'read with this correctiontherein Athat the same may conform tothe record of the case in thePatent Office.

Signed and sea-led thielst day of December, A. D. l9lIO.

Henry Van Arsdale, (Seal) Acting Commissioner ,of Patents.

